Endurance Fueling: How to Fuel to Go the Distance

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At InsideTracker we believe that eating is training. Eating is not only critical for workout fueling, but also for post endurance training recovery. Beyond what our biomarkers tell us, we recognize that it is important to eat to support training sessions and the recovery process in between.

This brings us to one of the most frequently asked questions sports dietitians hear, especially from those in the endurance sports world: "What should I be eating before and after my workouts?"

While the answer will vary between individuals and the activity to be performed, there are some basic guidelines and recommendations you can follow to help you nail your nutrition pre and post workout.

As an endurance athlete carbs are your friend! Carbohydrates are a critical source of fuel in exercise. 
The International Society of Sports Nutrition recommends a daily intake of 5-8 g/kg body weight for those who perform moderate to high intensity volume (defined as 2-3 hours per day, 5-6 days per week). This is to help maintain adequate levels of a stored form of carbohydrate, glycogen, that is found in both the liver and muscles. During longer bouts of physical activity (greater than 90 minutes) how your body uses carbohydrates will depend on a variety of factors including intensity and duration of exercise, how trained an individual us, and the usual diet of an individual.2 These stores of carbohydrate aren’t limitless, making eating a diet rich in carbohydrate an important piece of the puzzle to success in training for endurance sports.3  Endurance athletes fueling needs can be a bit tricky, an easy way to break it down, is by pre and post workout fueling. 


Eating pre-workout to boost your session:

Eating pre-workout will prevent hunger and optimize glycogen stores, delaying mental and muscle fatigue. This pre-workout fueling time frame should be approached as two parts. The first 2-4 hours from the start of your workout and the second being 30-60 minutes before your training session.

A high carbohydrate meal pre-workout has been shown to increase oxidation of carbohydrates, utilization of muscle glycogen, and improvements in performance in aerobic exercise.4 All things endurance athletes need to hit their longer training session! Note: this meal should have some protein to keep you satisfied and promote muscle recovery. Try to limit the fat, especially if eating under 2 hours pre-workout to avoid GI distress!

Not all workouts are created equal. Here are some things to consider before grabbing that pre-workout fuel:

The volume of the training cycle: Getting in those pre-workout carbs have a more significant impact for the athlete who is in a larger training cycle versus a rested or tapered state. When you’re consistently training at large volumes and with the intensity it's harder to keep up with restocking glycogen stores.5

Training intensity: When working at a higher heart rate, the body will burn glucose at a higher rate meaning you’ll need more fuel to maintain your workout! So when you’re heading into a day with more intensity such as a tempo run or climb crushing ride, starting off the session with adequate glycogen stores is extra crucial.

The Timing of Your Workouts: If you typically wake up early in the morning to train, nailing your pre-workout snack is extra critical! When you hit the pavement soon after waking you’re asking your body to perform after fasting for 7-8 hours while you sleep, increasing the potential for glycogen to be low. Without the time to have a carb-rich meal 2-4 hours before this session makes that snack 30-60 minutes before extra important!

2-4 hours pre-workout:

  • A turkey sandwich on whole grain bread with some vegetables and hummus or mustard paired with fruit.
  • 1 cup of pasta with chicken, spinach, and a few slices of zucchini or grape tomatoes.
  • Oatmeal with skim milk, a banana, and a few almonds.
  • Whole grain toast with peanut butter and jelly or honey.

30-60 minutes pre-workout:

  • 2-4 fat-free fig newtons
  • A toaster waffle with a tablespoon or two of maple syrup
  • Rice cake with jelly or jam

Corrine Malcom


When trying to balance work, life and training, getting your nutrition down can feel like a huge challenge. Corrine Malcolm, 2018 Canyon 100k winner and 2018 Western States 100 top 10 finisher gave us some tips on how she does all three while still making sure she fuels her body. ‘"With the schedule I have, I usually run directly into or through a meal so instead of having a carbohydrate and protein rich snack immediately after my run to get me to my next meal I’m eating that next meal. Some post run meals I’ve had include homemade butternut squash pie with an oatmeal crust with yogurt and coffee. Meal prepping and having extra food around that’s ready to go is extra important.”

Eat post-workout to nail your recovery:

You put in the hard work but now what? The post workout meal is the time where you can help your body get the most out of your training session. The goal of this is to promote muscle recovery and repair while re-stocking your glycogen stores.6 Putting in the practice of a good post-workout meal or snack will help you succeed in your next training session.

What should this post-workout snack or meal look like? The goal is for this to be a mix of carbohydrates and protein to help our bodies recover, especially when training for an endurance event. When these carbs are paired with protein post-exercise not only does the rate of glycogen synthesis increases it also creates a reduction in muscle damage, speeding up recovery time and promoting a healthy hormone balance.4 Opting for a moderate to high glycemic index carbohydrate immediately post-exercise has been shown to be a more effective choice for restoring glycogen.5

How much do you need of both carbs and protein post workout?

The ideal post-workout meal or snack is a 3-4:1 ratio of carbs to protein.4 Most tend to pump the protein, but for endurance athletes who have a high aerobic training volumes need to focus on carbs! Doing this will set you up for ideal recovery for your next session as you restore muscle glycogen and the protein promotes the repair of the muscles you just worked. Though no studies suggest a specific timing of this meal or snack, eating this just two hours after exercise can reduce glycogen synthesis by up to 50%.

Some suggestions:

Carbs: Sweet or regular potatoes, Rice, Quinoa, Fruit, Oatmeal

Protein: Eggs, Greek Yogurt, Chicken, Cottage Cheese, Whey or plant-based protein powders

Abby Levene, former competitive swimmer, NCAA D1 Track star, triathlete, and now ultra-runner echoes that same philosophy. “If I'm running or working out later in the day or out in the mountains without access to my kitchen, I try to bring a chocolate milk and a bag of sea salt and vinegar chips to rehydrate, refuel, and replenish my salt and satisfaction levels.”


The Science Behind The Fueling: 

How do you know if you’re getting enough of the nutrients your body needs to fuel and recover?  Cue #BloodDontLie. A few key biomarkers can show you what’s really going on inside after these hard training sessions and races.

hsCRP: A protein found in your blood that is most indicative of inflammation levels in the body.7 It has been shown that excessive physical activity can lead to increased levels in ultra-runners, marathoners, and triathlon racers.8 Inflammation in athletes can be combated with appropriate training and recovery strategies by avoiding significant increases in training, specifically run training. Three days of intense run training can result in substantial muscle damage in comparison to cyclists.9 Beyond adjusting your training approach, testing with InsideTracker provides personalized diet and supplementation strategies to help lower and manage inflammation levels between tests while monitoring potential future trends.

Cortisol: is a catabolic hormone secreted in response to physical and psychological stress. It plays a vital role in metabolism by helping to maintain blood glucose levels during exercise.5 Cortisol has also been found to be elevated when in a sleep-deprived state. Acute sleep deprivation has been shown to decrease cognitive function, have a negative effect on mood, and rate of perceived exertion. Cortisol should be highest in the morning and but then drop off slowly throughout the day.10

The Takeaway:

The timing and composition of the pre and post workout meals and snacks are important to perform and recover at your best. In addition to this, having a diet that includes a variety of foods that provides adequate energy, protein, fat, and carbohydrates is important for success. At InsideTracker we help you take this one step further with personalized nutrition recommendations including focus foods that are based on what your body needs. 

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1. Bytomski J. Fueling for Performance. Sports Health: A Multidisciplinary Approach. 2017;10(1):47-53. doi:10.1177/1941738117743913
2. Benardot D. Advanced Sports Nutrition. 2nd ed. Champaign, IL: Human Kinetics; 2012.
3. Mark A. Tarnopolsky MD, PhD, Martin Gibala, Asker E. Jeukendrup & Stuart M. Phillips (2005) Nutritional needs of elite endurance athletes. Part I: Carbohydrate and fluid requirements, European Journal of Sport Science, 5:1, 3-14, DOI: 10.1080/17461390500076741
4. Kerksick, C. M., Arent, S., Schoenfeld, B. J., Stout, J. R., Campbell, B., Wilborn, C. D., … Antonio, J. (2017). International society of sports nutrition position stand: nutrient timing. Journal of the International Society of Sports Nutrition, 14, 33. http://doi.org/10.1186/s12970-017-0189-4
5. Hawley, J., & Burke, L. (1997). Effect of meal frequency and timing on physical performance. British Journal of Nutrition, 77(S1), S91-S103. doi:10.1079/BJN19970107
6. Aragon, A. A., & Schoenfeld, B. J. (2013). Nutrient timing revisited: is there a post-exercise anabolic window? Journal of the International Society of Sports Nutrition, 10, 5. http://doi.org/10.1186/1550-2783-10-5
7. Kamath, Deepak Y. et al. “High Sensitivity C-Reactive Protein (hsCRP) & Cardiovascular Disease: An Indian Perspective.” The Indian Journal of Medical Research 142.3 (2015): 261–268. PMC. Web. 26 Apr. 2018.
8. Ertek, Sibel, and Arrigo Cicero. “Impact of Physical Activity on Inflammation: Effects on Cardiovascular Disease Risk and Other Inflammatory Conditions.” Archives of Medical Science : AMS 8.5 (2012): 794–804. PMC. Web. 26 Apr. 2018.
9. Nieman, David C., et al. “Immune and Inflammation Responses to a 3-Day Period of Intensified Running versus Cycling.” Brain, Behavior, and Immunity, vol. 39, 2014, pp. 180–185., doi:10.1016/j.bbi.2013.09.004.
10. DONALD, CIARAN MC et al. “Acute Effects of 24-H Sleep Deprivation on Salivary Cortisol and Testosterone Concentrations and Testosterone to Cortisol Ratio Following Supplementation with Caffeine or Placebo.” International Journal of Exercise Science 10.1 (2017): 108–120. Print.

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